1. Field of the Invention
The present invention relates to a valve seat made of Fe-based sintered alloy, as a structural member for internal combustion engines such as diesel engines, gasoline engines and the like.
2. Description of the Background
As disclosed in, for example, Japanese Unexamined Patent Publication No. 55-164063, Japanese Unexamined Patent Publication No. 58-178073 and the like, many valve seats have been proposed which are made of hard-particle dispersing type Fe-based sintered alloys as valve seats for internal combustion engines made of Fe-based sintered alloy. Recently, however, not only the production of internal combustion engines has greatly increased, but also the size of the engines has increased, which means that the valve seats, which are a structural member of the internal combustion engines, are compelled to operate in the environment of higher temperatures. However, when the conventional Fe-based sintered alloy valve seats and many other valve seats are used in the higher temperature environment of these engines, they are abruptly worn and their effective lives end in a relatively short period of time. A need continues to exist for valve seats of improved wear resistance, when exposed to higher temperature engine operating conditions.